Clinical data for the T-SPOT.TB test

Two Interferon Gamma Release Assays for Predicting Active Tuberculosis: The UK PREDICT TB Prognostic Test Study

Abubakar I, Drobniewski F, Southern J, et al. Prognostic value of interferon-γ release assays and tuberculin skin test in predicting the development of active tuberculosis (UK PREDICT TB): a prospective cohort study. The Lancet Infectious Diseases. 2018;18(10):1077-1087. doi:10.1061/S1473-3099(18)30355-4.

This large study compared the predictive value of TST, T-SPOT.TB and multi-tube ELISA for active TB development in 9,610 participants recruited from high risk populations.

Key findings in this paper include:

• The T-SPOT.TB test had the best positive predictive value of the three tests evaluated: it was significantly better than multi-tube ELISA (p < 0.0003), TST-5 (p < 0.0001), and TST-15 (p < 0.037)

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Evaluation of interferon-gamma release assay
(the T-SPOT.TB test) for diagnosis of tuberculosis infection in rheumatic disease patients

Jiang B, Ding H, Zhou L, Chen X, Chen S, Bao C Evaluation of interferon-gamma release assay (T-SPOT.TB) test for diagnosis of tuberculosis infection in rheumatic disease patients International Journal of Rheumatic Diseases 2016; 19: 38–42, 13 October 2015.

This prospective study was to evaluate the performance of the T-SPOT.TB test in the diagnosis of tuberculosis infection in rheumatic disease patients in China.

Key findings in this paper include:

• High specificity and sensitivity as well as high NPV are achieved by the T-SPOT.TB test but not with the TST

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T-SPOT.TB Interferon-γ Release Assay Performance in Healthcare Worker Screening at Nineteen U.S. Hospitals

King, TC, Upfa M, et al. T-SPOT.TB Interferon-γ Release Assay Performance in Healthcare Worker Screening at Nineteen U.S. Hospitals. American Journal of Respiratory and Critical Care Medicine, Vol. 192, No. 3 (2015), pp. 367-373. doi: 10.1164/rccm.201501 0199OC.

This landmark study of over 42,000 serial tests from 19 geographically diverse US hospitals demonstrates the performance of the T-SPOT.TB test. 

Key findings in this paper include:

• 98.9% concordance rate
• 0.8% mean conversion rate (negative result converting to a positive result)
• 17.6% mean reversion rate (positive result converting to a negative result)
• T-SPOT.TB results are strongly correlated to known tuberculosis (TB) risk factors
• This study demonstrated the T-SPOT.TB test is a reliable tool for healthcare worker screening

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T-cell profiling and the immunodiagnosis of latent tuberculosis infection in patients with inflammatory bowel disease.

Arias-Guillén M, Riestra S, de Francisco R, Palacios JJ, Belda J, Escalante P, Pérez-Martínez I, Molinos LM, Garcia-Clemente M, Pando-Sandoval A, Rodrigo L, Prieto A, Martínez-Camblor P, Losada A, Casan P. T-cell profiling and the immunodiagnosis of latent tuberculosis infection in patients with inflammatory bowel disease. Inflamm Bowel Dis. 2014 Feb;20(2):329-38.

The study was designed to investigate the performance, and the factors associated with performance of IGRAs and the tuberculin skin test (TST) in screening for latent tuberculosis infection in patients with inflammatory bowel diseases (IBD).

Key findings:

• Diagnostic performance of the T-SPOT.TB test is less affected by corticosteroid treatment than the multi-tube ELISA

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Screening health care workers with interferon-γ release assay versus tuberculin skin test: Impact on costs and adherence to testing (the SWITCH study)

Bernacki E, Humphrey F, Sneed L, Tao X, Wrighton-Smith P. “Screening health care workers with interferon-γ release assay versus tuberculin skin test: impact on costs and adherence to testing (the SWITCH study).” J Occup Environ Med. 2012 Jul;54(7):806-15. doi: 10.1097/JOM.0b013e318254620f.

This landmark study is the first-of-its-kind to analyze the actual cost of a TB surveillance program using the tuberculin skin test (TST) or the T-SPOT.TB test by obtaining direct measurements of all program components.

Key findings in this paper include:

• The study exposes the false economics of the TST, demonstrating that it actually costs $73.20 per test to perform when accounting for all components of a TST screening program
• A test price of $54.83 or lower for the T-SPOT.TB test is more cost-effective than the TST
• T-SPOT.TB compliance was 99%; increasing the TST compliance to 98.5% would cost an additional $20.59 per employee

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Effect of immunosuppressive therapy on interferon γ release assay for latent tuberculosis screening in patients with autoimmune diseases: a systematic review and meta-analysis

Sunny H Wong et al, Effect of immunosuppressive therapy on interferon γ release assay for latent tuberculosis screening in patients with autoimmune diseases: a systematic review and meta-analysis Thorax 2016;71:64–72.

This meta-analysis was carried out with the aim to summarise the existing data on the effect of immunosuppressive therapy on IGRA performance in patients with autoimmune disorders.

Key findings in this paper include:

• IGRAs are affected by immunosuppressive therapy, but the T-SPOT.TB test may be less affected than the other IGRA.

Impact of peripheral lymphocyte count on the sensitivity of 2 IFN-γ release assays, QFT-G and ELISPOT, in patients with pulmonary tuberculosis

Komiya K, Ariga H, Nagai H, et al. Impact of peripheral lymphocyte count on the sensitivity of 2 IFN-γ release assays, QFT-G and ELISPOT, in patients with pulmonary tuberculosis. Internal Medicine. 2010;49(17):1849-1855. Doi:10.2169/internalmedicine.49.3659

This study investigating the effect of cell number on the sensitivity of the multi-tube ELISA and the T-SPOT.TB test showed that a reduction in cell numbers affected the sensitivity of the multi-tube ELISA, whereas the T-SPOT.TB test was relatively unaffected.

A key finding in this study include:

• Overall sensitivity of 74% for the multi-tube ELISA, compared to 92% for the T-SPOT.TB test
• The multi-tube ELISA showed a reduction in sensitivity at lymphocyte counts below 1.0×10³ cells/mL
• The T-SPOT.TB test maintained >80% sensitivity even at lymphocyte counts below 1.0×10³ cells/mL

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Diagnostic performance of whole-blood interferon-γ assay and enzyme-linked immunospot assay for active tuberculosis

Lai CC, Tan CK,et al. Diagnostic performance of whole-blood interferon-γ assay and enzyme-linked immunospot assay for active tuberculosis. J Microbiol Immunol Infect. 2011 Oct;44(5):406-7. doi: 10.1016/j.jmii.2011.07.002. Epub 2011 Sep 8.

This study compared the diagnostic performance of two interferon-gamma release assays in patients with suspected active TB.

Key findings in this paper include:

• The T-SPOT.TB test had less false negative results, especially in immunocompromised patients, compared to the other commercially available IGRA
• The T-SPOT.TB test had a higher sensitivity than the other commercially available IGRA

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Interferon gamma release assays for diagnostic evaluation of active tuberculosis (IDEA): test accuracy study and economic evaluation

Takwoingi Y, Whitworth H, Rees-Roberts M, et al. Interferon gamma release assays for Diagnostic Evaluation of Active tuberculosis (IDEA): test accuracy study and economic evaluation. Health Technol Assess. 2019;23(23):1-152. doi:10.3310/hta23230

This prospective study compared the accuracy and cost-effectiveness of the T-SPOT.TB test, the multi-tube ELISA, and a modified T-SPOT test (in which the ESAT-6 antigen was replaced with Rv3615c) for identifying active vs. latent TB in TB suspects.

Key findings from this study include:

• The T-SPOT.TB test had significantly higher sensitivity (82.3%) than the multi-tube ELISA (67.3%) for differentiating those with active TB from those in which active TB was excluded
• The T-SPOT.TB test was more cost-effective than the multi-tube ELISA

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Diagnostic value of the interferon-γ release assay for tuberculosis infection in patients with Behcet’s disease

Wu X, Chen P, Wei W, et al. Diagnostic value of the interferon-γ release assay for tuberculosis infection in patients with Behçet’s disease. BMC Infectious Diseases. 2019;19(1):323. doi: 10.1186/s12879-019-3954-y

This study tested the ability of the T-SPOT.TB test to detect tuberculosis in patients with Behçet’s disease, an autoimmune inflammatory disease of blood vessels.

Key findings in this study include:

• The T-SPOT.TB test had a sensitivity of 88.9%, and a specificity of 74.8% in patients with Behçet’s disease
• This paper adds to the evidence that T-SPOT.TB works well in immunosuppressed patients

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Summary of key clinical studies

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T-SPOT.TB package insert

The T-SPOT.TB test is an in vitro diagnostic test for the detection of effector T cells that respond to stimulation by Mycobacterium tuberculosis antigens ESAT-6 and CFP10 by capturing interferon-gamma (IFN-γ) in the vicinity of T cells in human whole blood collected in sodium citrate or sodium or lithium heparin. It is intended for use as an aid in the diagnosis of M. tuberculosis infection.